bsd: export recv() correctly

3c16063a forgot to make recv() as having C linkage.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

bsd/sys/kern/uipc_syscalls_wrap.cc

@@ -154,6 +154,7 @@ ssize_t recvfrom(int fd, void *__restrict buf, size_t len, int flags,
 	return bytes;
 }
 
+extern "C"
 ssize_t recv(int fd, void *buf, size_t len, int flags)
 {
 	int error;